/**
 * Http管理器
 * 
 */

import { sys } from "cc";
import SubManager from 'db://assets/Scripts/Sub/SubManager';

// 请求类型
export type HttpMethod = "GET" | "POST" | "PUT";
// 请求参数结构
export interface HttpSendOptions {
  headers?: Record<string, string>;
  responseType?: XMLHttpRequestResponseType;
  rawBody?: Document | XMLHttpRequestBodyInit | null;
}
// 响应结构
export interface HttpRawResponse {
  ok: boolean;              // 是否 2xx
  status: number;           // HTTP 状态码，网络错误/超时为 0
  body?: any;               // xhr.response 或 xhr.responseText
  error?: "timeout" | "network" | "http";
}

export class HttpManager {
  private static _I: HttpManager | null = null;
  public static get I(): HttpManager {
    if (!HttpManager._I) HttpManager._I = new HttpManager();
    return HttpManager._I;
  }
  private constructor() {}

  /** 发起请求，供 ApiClient 使用 */
  public async request(
    url: string,
    data: any,
    method: HttpMethod = "GET",
    opt: HttpSendOptions = {}
  ): Promise<HttpRawResponse> {
    const xhr = new XMLHttpRequest();
    // 超时
    xhr.timeout = 10000;
    // 响应类型
    if (opt.responseType) xhr.responseType = opt.responseType;

    if (method === "GET") {
      url = url + this.buildQuery(data);
      xhr.open(method, url, true);
      if (sys.isNative) {
        xhr.setRequestHeader("Accept-Encoding", "gzip,deflate");
        xhr.setRequestHeader("content-type", "text/html;charset=utf-8");
      }
    } else {
      xhr.open(method, url, true);
      if (!opt.rawBody) {
        xhr.setRequestHeader("Content-Type", "application/json");
      }
    }
    if (opt.headers) {
      Object.keys(opt.headers).forEach(k => xhr.setRequestHeader(k, opt.headers![k]));
    }

    return new Promise<HttpRawResponse>((resolve) => {
      xhr.onreadystatechange = () => {
        if (xhr.readyState === 4) {
          const ok = xhr.status >= 200 && xhr.status < 300;
          const body = xhr.response ?? xhr.responseText ?? null;
          if (!ok) {
            SubManager.ShowPrompt(`网络错误(${xhr.status})，请稍后再试`);
          }
          resolve({ ok, status: xhr.status, body, error: ok ? undefined : "http" });
        }
      };
      xhr.onerror = () => {
        SubManager.ShowPrompt("网络错误，请检查网络连接");
        resolve({ ok: false, status: 0, error: "network" });
      };
      xhr.ontimeout = () => {
        SubManager.ShowPrompt("请求超时，请检查网络连接");
        resolve({ ok: false, status: 0, error: "timeout" });
      };

      if (method === "GET") {
        xhr.send();
      } else {
        if (opt.rawBody !== undefined) xhr.send(opt.rawBody ?? null);
        else xhr.send(JSON.stringify(data ?? {}));
      }
    });
  }

  /**
   * 把对象转 ?a=1&b=2 的查询串
   */  
  private buildQuery(json: any) {
    if (!json || typeof json !== "object") return "";
    const pairs = Object.keys(json).map(
      k => encodeURIComponent(k) + "=" + encodeURIComponent(json[k])
    );
    return pairs.length ? "?" + pairs.join("&") : "";
  }
}